We got early Slav samples from Bohemia and Avar-Slavic ones, also Iron Age Bulgarian so it shouldn't be too hard to make nMonte model. Add Bulgars and Myceneans in the mix if they are available.

As far as i know we have two early Slavs from Avar Hungary and two from Slavic Bohemia. One was West Slavic-like and the other Belarusian-like. In Slavic Bohemia one was also West Slavic-like and other more Baltic-shifted. So i would say that Proto-Slavs were East Polish/South Belarusian-like and that very much fits archaeology and linguistics which pinpoint the slavic homeland somewhere in northern Ukraine/Belarus (Kiev culture)